Artykuły w czasopismach: „Effect of dredging”

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Zhong, Ji-Cheng, Ju-Hua Yu, Xiao-Lan Zheng, Shuai-Long Wen, De-Hong Liu i Cheng-Xin Fan. "Effects of Dredging Season on Sediment Properties and Nutrient Fluxes across the Sediment–Water Interface in Meiliang Bay of Lake Taihu, China". Water 10, nr 11 (8.11.2018): 1606. http://dx.doi.org/10.3390/w10111606.

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The influence of dredging season on sediment properties and nutrient fluxes across the sediment–water interface remains unknown. This study collected sediment cores from two sites with different pollution levels in Meiliang Bay, Taihu Lake (China). The samples were used in simulation experiments designed to elucidated the effects of dredging on internal loading in different seasons. The results showed that dredging the upper 30 cm of sediment could effectively reduce the contents of organic matter, total nitrogen, and total phosphorus in the sediments. Total biological activity in the dredged sediment was weaker (p < 0.05) than in the undredged sediment in all seasons for both the Inner Bay and Outer Bay, but the effect of 30-cm dredging on sediment oxygen demand was negligible. Dredging had a significant controlling effect on phosphorus release in both the Inner Bay and Outer Bay, and soluble reactive phosphorus (SRP) fluxes from the dredged cores were generally lower (p < 0.05) than from the undredged cores. In contrast, NH4+-N fluxes from the dredged cores were significantly higher (p < 0.05) than from the undredged cores in all seasons for both sites, this indicates short-term risk of NH4+-N release after dredging, and this risk is greatest in seasons with higher temperatures, especially for the Inner Bay. Dredging had a limited effect on NO2−-N and NO3−-N fluxes at both sites. These results suggest that dredging could be a useful approach for decreasing internal loading in Taihu Lake, and that the seasons with low temperature (non-growing season) are suitable for performing dredging projects.

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Boulcott, Philip, Colin P. Millar i Rob J. Fryer. "Impact of scallop dredging on benthic epifauna in a mixed-substrate habitat". ICES Journal of Marine Science 71, nr 4 (3.01.2014): 834–44. http://dx.doi.org/10.1093/icesjms/fst197.

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Abstract Experimental scallop dredging was conducted to assess the vulnerability of emergent epifauna on hard substrates. Three sites were sampled before and after dredging to examine changes in the coverage of faunal turf (hydroid and bryozoan) assemblages and the composition of the wider epifaunal community. Each site had an “impact” box that was dredged, a control box that was in an area that was still open to fishing, and a control box in a special area of conservation (SAC) that had not been fished for two years. Community composition differed significantly after dredging in two of the three sites, with dredged communities becoming less similar to those in the SAC. There was no clear evidence that dredging in the impact boxes reduced the coverage of faunal turfs on hard substrates. However, the coverage of faunal turfs on hard substrates in the SAC was typically greater than in areas that were still being fished commercially, consistent with a dredging effect. The results highlight the role that substrate morphology might play in modifying the severity of dredging effects. This has relevance to marine spatial management, as it suggests that emergent epifauna living on hard substrates that are morphologically suited to dredging, such as pebble and cobble substrates, could be particularly vulnerable to dredging.

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Garcia Renteria, Francisco Fernando, i Mariela Patricia Gonzalez Chirino. "Effect of bathymetric changes on residence time in Buenaventura bay (Colombia)". DYNA 86, nr 211 (1.10.2019): 241–48. http://dx.doi.org/10.15446/dyna.v86n211.79649.

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In order to study the effects of dredging on the residence time of the water in Buenaventura Bay, a 2D finite elements hydrodynamic model was coupled with a particle tracking model. After calibrating and validating the hydrodynamic model, two scenarios that represented the bathymetric changes generated by the dredging process were simulated. The results of the comparison of the simulated scenarios, showed an important reduction in the velocities fields that allow an increase of the residence time up to 12 days in some areas of the bay. In the scenario without dredging, that is, with original bathymetry, residence times of up to 89 days were found.

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Adesina, Thomas Kehinde, i Ogunnowo Aderonke Adunola. "Perceived Effects of Sand Dredging on Livelihood Diversification of Artisanal Fisher Folks in Lagos State, Nigeria". Agricultura Tropica et Subtropica 50, nr 2 (27.06.2017): 71–79. http://dx.doi.org/10.1515/ats-2017-0008.

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AbstractThe study examined perceived effects of sand dredging activities on livelihood diversification of artisanal fisher folks in Lagos State, Nigeria. Multi-stage sampling procedure was used to select respondents for the study. Purposively, Eti-Osa, Ibeju-Lekki, Epe and Ikorodu local Government Areas (LGAs) were selected for intensive dredging activities. Registered artisanal fishermen in these LGAs were 310, 350, 380 and 320, respectively. Twenty percent of the population in each LGAs were selected using simple random sampling technique to arrive at 272 respondents interviewed for the study. An interview schedule guide was used to elicit information on respondents’ socio-economic characteristics, knowledge, livelihood diversification and perception of the sand dredging effect on fishing activities. Data were analyzed using descriptive statistics, Pearson Product Moment Correlation and independent sample t-test. The mean age of fisher folks was 37 ± 8 years, 92.1 % of them were males, 81.4 % were married and had households’ size ranging from 1 to 16 persons. Over 50 % of the respondents had no formal education. Monthly income of fisher folks in the study area ranged from ₦5, 000 to ₦60, 000 with a mean income of ₦22, 892 ± 13,564 and majority (92.9 %)were members of a social group. Respondents diversified most into off-farm activities such as commercial bike riding, security and technician services. Slightly above half (55.7 %) perceived sand dredging as having a negative effect on fishing activities. Results on inferential statistic revealed that a significant relationship existed between knowledge of sand dredging effect on fishing activities (r = 0.35), monthly income (r = −0.181) and social group (χ2= 2.886) and perceived effects of sand dredging on fishing activities. Deliberate policy drive to mitigate sand dredging practices is required to forestall the negative effect on livelihood diversification of the artisanal fisher folks. Consequently, the artisanal fishery contribution to total Gross Domestic Product (GDP), employment generation and total domestic fish production will be enhanced.

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Campmans, G. H. P., P. C. Roos, N. R. Van der Sleen i S. J. M. H. Hulscher. "Modeling tidal sand wave recovery after dredging: effect of different types of dredging strategies". Coastal Engineering 165 (kwiecień 2021): 103862. http://dx.doi.org/10.1016/j.coastaleng.2021.103862.

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Barry, Jon, Sian Boyd i Robert Fryer. "Modelling the effects of marine aggregate extraction on benthic assemblages". Journal of the Marine Biological Association of the United Kingdom 90, nr 1 (19.08.2009): 105–14. http://dx.doi.org/10.1017/s0025315409990737.

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This paper develops models of the initial impact of marine aggregate extraction on a benthic assemblage. We predict the effect of dredging on species numbers and abundance assuming spatial randomness of individuals. We extend the model to allow for spatial clustering of individuals using a Matern process. Data from a controlled field experiment are used to develop a framework for estimating species reduction. This involves modelling the spatial pattern of individuals before dredging using a Matern process, the impact of dredging at an individual level, and the probability that a species is not seen in a post-dredging survey. The framework was used to estimate that, of the 41 species that were seen in a pre-dredging survey but not in a post-dredging survey, between 0 and 14 were eliminated (with 95% likelihood) rather than escaped detection. The most likely number eliminated was 4.

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Jicheng, ZHONG, LIU Guofeng, FAN Chengxin, BAI Xiuling, LI Bao, ZHANG Lu i DING Shiming. "Environmental effect of sediment dredging in lake: Ⅲ. Influence of dredging on denitrification in sediments". Journal of Lake Sciences 21, nr 4 (2009): 465–73. http://dx.doi.org/10.18307/2009.0403.

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Irawan, Dani. "Effect of Dredging Rate, Sintering Time, Cooling Media on Corrosion Results of Carbon Steel Dredging". International Journal of Science, Engineering and Information Technology 5, nr 02 (27.07.2021): 254–59. http://dx.doi.org/10.21107/ijseit.v5i02.6023.

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Metal reinforcement that has an impact on improving mechanical properties can occur in various ways, including by strain hardening mechanisms, solid solutions, second phase, prespitations, disperse, grain refinement and texture. In recent years, another method has been developed to obtain good mechanical properties without adding alloy elements, namely by the method of comprehensive plastic deformation (Severe Plastic Deformation). The purpose of this research is to conduct a study of rolling using medium carbon steel with a treatment temperature above recrystallization, rolling rate, sintering time, cooling media as an effort to develop and design new innovations about steel structures being rolled. The study of developing rolling techniques that can be applied in industry and can be applied as learning material / media in higher education requires structured research stages. The best impact value from this temper process is a temperature of 550 ° C for 1 hour where the impact value is 1.58 J / mm² with air conditioning media. In the rolling process above the recrystallization temperature 800 ° C deformation 20% the impact value is 1.7 J / mm² where the toughness indicates a ductile fracture while the deformation is 10% the impact value

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McLaverty, C., OR Eigaard, GE Dinesen, H. Gislason, A. Kokkalis, AC Erichsen i JK Petersen. "High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems". Marine Ecology Progress Series 642 (28.05.2020): 21–38. http://dx.doi.org/10.3354/meps13330.

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Commercial dredging for blue mussels (Mytilus edulis) and oysters (Ostrea edulis, Crassostrea gigas) constitute the main bivalve fisheries in Denmark. These activities predominantly take place in Limfjorden, a large microtidal sound, and in the Inner Danish waters. Both areas are shallow, estuarine, receive high nutrient inputs from agriculture, and are of nature conservation interest (Natura 2000 sites), thus presenting challenges for an ecosystem approach to fisheries management. Using high-resolution fisheries data (~10 m), we investigated the effects of bivalve dredging on benthic communities at both local (Natura 2000 site) and regional (fishery-wide) scales. Regionally, our results showed that dredging intensity correlated with shifts in species composition and reduced community biomass. We were, however, unable to detect an effect of dredging on community density, trait richness, and trait composition. These metrics were significantly related to other environmental drivers, such as sediment organic content (negative) and mussel bed biomass (positive). At the local scale, the observed relationships between dredging, biomass, and species composition varied significantly. This occurred as dredging impacts were greater in areas that contained suitable reference conditions and experienced relatively low levels of disturbance. By contrast, communities which experienced high nutrient loading, regular anoxic events, and high natural variability were relatively unaffected by dredging. Our results therefore highlight the importance of spatial scales in fishing impact estimations. Furthermore, we demonstrate how targeted sampling, high-resolution fisheries data, and suitable reference areas can be used to detect fishery effects in coastal areas that are highly stressed by eutrophication.

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Islam, Md Kabirul, Numan Al Kibriya i Md Maruf Dustegir. "Impact Analysis of Sand Dredging from Alluvial Tidal River". E3S Web of Conferences 40 (2018): 03036. http://dx.doi.org/10.1051/e3sconf/20184003036.

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The Government of Bangladesh has planned to make a large build up area (BUA) in a newly developed sedimentary point bar (locally known as ‘Char’) at Lebukhali along the northern bank of Payra river in the southern part of the country. From a study it was revealed that, this sedimentary bar has to be raised by 3.45 meters from MSL to keep it free from any extreme events (like tidal and storm surge effects) for 100 years return period. Accordingly, it was planned to collect the required filling material (estimated 57.6 million m3 of sand/soil) by dredging the same river bed. In Bangladesh dredging of river is very popular and widely undertaken to collect filling and construction material, but its adverse impact on river bed, bank and adjacent areas are hardly probed. This study aimed at analyzing the adverse impacts of dredging from Payra River bed. Four alternative sand bars have been identified as dredging area at varying distances located both upstream and downstream of the proposed site. The dredging impacts were analyzed for different boundary conditions. The study is based on physical survey (topographic and bathymetric surveys), historical data and numerical model analysis. Numerical model is applied through Delf 3D to investigate the impact on flow parameters: flood depth and velocity magnitude. Continuous field visit and observations were made through last one year to observe real impact. The analysis revealed that dredging of any of the bars have resulted changes in flow field. The distance of dredging point does not control the flow field rather the dredging volume, depth and upstream conditions determine the effect on bank erosion. As such, the dredging locations have been prioritized considering the least possible effects on river bank erosion and founded that little erosion is taking place for both upstream and downstream region. However, the long term impacts in other areas of the river need to be investigated as the time pass.

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Muthukkumaran, Kasinathan, i Ranganathan Sundaravadivelu. "Numerical modeling of dredging effect on berthing structure". Acta Geotechnica 2, nr 4 (3.11.2007): 249–59. http://dx.doi.org/10.1007/s11440-007-0040-1.

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Stoddart, James, Ross Jones, Cathie Page, Michael Marnane, Paul De Lestang i Travis Elsdon. "No effect of dredging on the prevalence of coral disease detected during a large dredging program". Marine Pollution Bulletin 140 (marzec 2019): 353–63. http://dx.doi.org/10.1016/j.marpolbul.2019.01.047.

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De Lacerda, Luiz Drude, Ingra Kellen Belmino Belmino, Lucas Buruaem Moreira i Rozane Valente Marins. "EFFECT OF DREDGING ON HG DISTRIBUTION IN WATER AND SEDIMENTS IN THE MUCURIPE HARBOR, FORTALEZA, NE BRAZIL". Arquivos de Ciências do Mar 52, nr 2 (11.03.2020): 77–84. http://dx.doi.org/10.32360/acmar.v52i2.42167.

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Dredging and tailings disposal can mobilize mercury (Hg) accumulated in bottom sediments, increasing the exposure of the aquatic biota. In the Mucuripe Harbor, NE, Brazil, dredging is performed regularly, but the impact on Hg mobilization is unknown. This paper presents results from the monitoring of a dredging operation to characterize and quantify an eventual Hg mobilization. The results showed that remobilization is significant and is associated with suspended solids. Further deposition of the Hg-enriched, remobilized, suspended solids increased Hg concentrations by a factor of 1.2 and 2.0 in harbor and shelf sediments, respectively. Maximum concentrations in harbor and shelf sediments reached 79.9 ng.g-1 and 32.4 ng.g-1 (20 and 9 higher than the regional background, respectively). The progressive increase in Hg concentrations may result in higher exposure to the local biota.Keywords: metals, mobilization, contamination, coastal sediments.

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Stępień, Edyta, Andrzej Zawal, Paweł Buczyński, Edyta Buczyńska i Magdalena Szenejko. "Effects of dredging on the vegetation in a small lowland river". PeerJ 7 (22.01.2019): e6282. http://dx.doi.org/10.7717/peerj.6282.

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Background Conventional river engineering operations have a substantial influence on the fluvial ecosystem. Regulation and channelization generally reduce the physical heterogeneity of river beds and banks and the heterogeneity of habitats. They determine the character, diversity and species richness of plant communities. The effect of river regulation on vegetation has been repeatedly investigated, but few studies have been conducted within reaches of previously regulated rivers. The aim of this work is to expand and current knowledge about the impact of dredging on the vegetation of a regulated section of a lowland river. Materials & Methods The study included pre-dredging (1 year before) and post-dredging surveys (results 1 and 2 years after dredging). The vegetation was analysed in terms of species composition, origin of species, life forms, distribution of Grime’s life strategies, and selected ecological factors. The Shannon–Wiener biodiversity index (H) and evenness were also analysed in each year of the study. The impact of dredging on the vascular flora was assessed by ‘before-after-control-impact’ (BACI) analysis. Results The number of species and biodiversity as measured by the Shannon–Wiener index (H) increased in the analysed section of the river valley. However, enrichment of the flora was observed only on the floodplain, on the surface of the deposited dredging material, while the number of species in the river channel decreased, as dredging of the river bed and levelling of the banks had markedly reduced habitat diversity. Although species richness in the second year after the dredging approached the values recorded before the intervention, the absence of particularly species or phytocenoses associated with shallow river banks and sandbars was still observed. The change in habitat conditions and the destruction of the vegetation cover during the dredging enabled penetration by numerous previously unrecorded alien species of plants and apophytes. There was a perceptible increase in the role of therophytes in the flora. It is worth noting that the number of alien species and therophytes declined significantly in the second year after the dredging. Analysis of the proportions of species representing various life strategies showed that previously unrecorded species with the type R (ruderal) life strategy had appeared, representing by pioneer species occurring in frequently disturbed habitats. There was also a marked increase in the share of species representing the mixed C-R (competitive-ruderal) strategy, occurring in habitats with low levels of stress, whose competitive abilities are limited by repeated disturbances. By the second year after the dredging, however, these changes were largely no longer observed. Conclusions Through appropriate maintenance of the regulated river, it can be rapidly recolonized by vegetation after the procedure, but it may lead to the loss of some species and phytocoenoses.

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Chao, Lei, Xiaoyun Mo, Jia Meng i Yafeng Li. "Study on enhanced bioremediation effect of oil-bearing dredging sediment". E3S Web of Conferences 252 (2021): 02031. http://dx.doi.org/10.1051/e3sconf/202125202031.

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To solve the problem of difficult treatment of oil-bearing dredging sediment, the effects of three methods of microbial remediation, phytoremediation and combined bioremediation on the treatment of oily river dredging sediments were compared and studied, and the influence factors of microbial remediation were explored through static bacteria-fling tests. The results showed that the combined remediation method was better than the single biological method in treating bottom mud. The oil content of the treated sediment was 1.21g/kg, and the removal rate was 95.31%; the organic matter of the treated sediment was 72.30g/kg, and the degradation rate was 37.33. %, which can meet the requirements in the “Control Standards of Pollutants in Sludge for Agricultural Use (GB4284–2018)” and can be used for agricultural purposes.

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Jicheng, ZHONG, LIU Guofeng, FAN Chengxin, Zhang Lu, DING Shiming i Ren Xiaolong. "Environmental effect of sediment dredging in lake (I): the role of sediment dredging in reducing internal phosphorous release". Journal of Lake Sciences 21, nr 1 (2009): 84–93. http://dx.doi.org/10.18307/2009.0111.

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Jicheng, ZHONG, LIU Guofeng, FAN Chengxin, LI Bao, ZHANG Lu i DING Shiming. "Environmental effect of sediment dredging in lake: Ⅱ. the role of sediment dredging in reducing internal nitrogen release". Journal of Lake Sciences 21, nr 3 (2009): 335–44. http://dx.doi.org/10.18307/2009.0304.

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Feng, Lu-Da, Yang Tian, Xin Wang, Run Dai, Song Cai, Yu-Jia Cao i Yin-Chu Si. "Therapy of Dredging the Bowels Enhanced the Neuroprotective Effect of Nourishing Kidney Herbs on Hippocampal Cholinergic System in Alzheimer’s Disease Model Rat Induced by Aβ 1-42". Evidence-Based Complementary and Alternative Medicine 2018 (12.09.2018): 1–12. http://dx.doi.org/10.1155/2018/3282385.

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Background. Therapy of nourishing kidney has been used for treating memory deficits of Alzheimer’s disease (AD) for thousands of years based on traditional Chinese medicine. However, we found the therapy of dredging the bowels could alleviate both memory deficits and mental symptoms of AD in clinic. Objective. To determine whether the therapy of dredging the bowels could enhance the neuroprotective effect of nourishing kidney herbs for treating AD rats, and to explore the underlying mechanism of the combination of nourishing kidney and dredging the bowels (NKDB) herbs. Methods. 60 rats were randomly divided into sham-operated group (SOG), model group (MG), nourishing kidney group (NKG), dredging the bowels group (DBG), nourishing kidney and dredging the bowels group (NKDBG), and donepezil hydrochloride group (DHG). The model establishment was performed by injecting Aβ 1-42 into the hippocampal CA1 region. Animals received aqueous solution of Chinese herbal medicine or western medicine while SOG received only distilled water. Ability of learning and memory were assessed by Morris water maze. Acetylcholinesterase(AChE) and choline acetyltransferase (ChAT) activity and positive cells in the hippocampus were detected by the biochemical and immunofluorescent assay. Results. All rats were in the same baseline. While after model establishment, ability of learning and memory of MG, NKG, DBG, NKDBG, and DHG were significantly impaired compared with SOG. Whereas after treatment, ability of learning and memory of NKG, DBG, NKDBG, and DHG were significantly improved compared with MG. Additionally, AChE activity of NKG, DBG, and NKDBG was significantly decreased, meanwhile ChAT activity showed an increased tendency. The number of AChE-positive cells and ChAT-positive cells of both NKDBG and DHG were significantly decreased and increased respectively, superior to those when compared with NKG and DBG. What’s more, there was no significant difference between NKDBG and DHG. Conclusion. Therapy of dredging the bowels could enhance the neuroprotective effect of nourishing kidney herbs by reversing morphological damage of hippocampal cholinergic system. Furthermore, treatment with NKDB herbs could be effectively against AD, providing a practical therapeutic strategy in clinic.

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Miller, Margaret W., Jocelyn Karazsia, Carolyn E. Groves, Sean Griffin, Tom Moore, Pace Wilber i Kurtis Gregg. "Detecting sedimentation impacts to coral reefs resulting from dredging the Port of Miami, Florida USA". PeerJ 4 (17.11.2016): e2711. http://dx.doi.org/10.7717/peerj.2711.

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The federal channel at Port of Miami, Florida, USA, was dredged between late 2013 and early 2015 to widen and deepen the channel. Due to the limited spatial extent of impact-assessment monitoring associated with the project, the extent of the dredging impacts on surrounding coral reefs has not been well quantified. Previously published remote sensing analyses, as well as agency and anecdotal reports suggest the most severe and largest area of sedimentation occurred on a coral reef feature referred to as the Inner Reef, particularly in the sector north of the channel. A confounding regional warm-water mass bleaching event followed by a coral disease outbreak during this same time frame made the assessment of dredging-related impacts to coral reefs adjacent to the federal channel difficult but still feasible. The current study sought to better understand the sedimentation impacts that occurred in the coral reef environment surrounding Port of Miami, to distinguish those impacts from other regional events or disturbances, and provide supplemental information on impact assessment that will inform discussions on compensatory mitigation requirements. To this end, in-water field assessments conducted after the completion of dredging and a time series analysis of tagged corals photographed pre-, during, and post-dredging, are used to discern dredging-related sedimentation impacts for the Inner Reef north. Results indicate increased sediment accumulation, severe in certain times and places, and an associated biological response (e.g., higher prevalence of partial mortality of corals) extended up to 700 m from the channel, whereas project-associated monitoring was limited to 50 m from the channel. These results can contribute to more realistic prediction of areas of indirect effect from dredging projects needed to accurately evaluate proposed projects and design appropriate compliance monitoring. Dredging projects near valuable and sensitive habitats subject to local and global stressors require monitoring methods capable of discerning non-dredging related impacts and adaptive management to ensure predicted and unpredicted project-related impacts are quantified. Anticipated increasing frequency and intensity of seasonal warming stress also suggests that manageable- but- unavoidable local stressors such as dredging should be partitioned from such seasonal thermal stress events.

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Rodrigues, Paloma de Almeida, Rafaela Gomes Ferrari, Rachel Ann Hauser-Davis, Luciano Neves dos Santos i Carlos Adam Conte-Junior. "Dredging Activities Carried Out in a Brazilian Estuary Affect Mercury Levels in Swimming Crabs". International Journal of Environmental Research and Public Health 17, nr 12 (18.06.2020): 4396. http://dx.doi.org/10.3390/ijerph17124396.

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(1) Although suffers from intense pollution inputs, Guanabara Bay, the most socioeconomically and environmentally important estuary in Rio de Janeiro, Brazil, is still home to a diverse fauna, including several fish and crab species consumed by humans. The bay presents high sedimentation rates and sediment contamination, further aggravated by dredging processes carried out in recent years. In this context, this study aimed to verify the effect of the dredging process on total mercury (THg) concentrations at Guanabara Bay through swimming crab assessments sampled before (2016), during (2017), and after (2018) the dredging process, and mainly, if the detected concentrations can be harmful to consumer health; (2) Methods: Swimming crab samplings were carried out at the same time and sampling points in 2016, 2017 and 2018 and the total Hg was determined using a Direct Mercury Analyzer (DMA-80, Milestone, Bergamo, Italy); (3) Results: Increased Hg concentrations were observed during the dredging process, decreasing to lower values, close to the initial concentrations, at the end of the process. Some of the investigated abiotic factors favor Hg dynamics in the aquatic environment, while others were positively altered at some of the assessed sampling areas at the end of the dredging process; (4) Conclusions: Although crab Hg levels were below maximum permissible limits for human consumption, it is important to note that these animals are significantly consumed around Guanabara Bay, which may lead to public health issues in the long term.

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Deng, Jin Feng, Qing Bin Sun, Hong Juan Zhu, Chun Qin Yin, Su Ping Rao i Zhu Xiao. "Key Nutriments Persistence with Various Loading of Phosphorus Pollution in Cihu Lake, China". Advanced Materials Research 726-731 (sierpień 2013): 3203–11. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3203.

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Dredging is the available method to clarify eutrophic lake water for some engineers in recent years. This engineering may cause at least two negative influences on water environment, (a) pollution by dredging would occur during the operation, and (b) long-term effect degrade with some lake become dirty subsequently. Changes of the concentration of TP after the engineering of dredging are the focus in this paper. The content of total carbon (TC) and total nitrogen (TN) change at the same time for different original concentration of TP. Five grade original concentration of TP was simulated and the changing law was presented with the process of duration (D) and the change of temperature (T) as the independent variables. The results indicated that the concentration of TP decreased almost to 50% of their original ones respectively. But the changes of concentrations of TN and TC abide by the distinguished rule.

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Gaspar, M. B., M. N. Santos, F. Leitão, L. Chícharo, A. Chícharo i C. C. Monteiro. "Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge". Journal of the Marine Biological Association of the United Kingdom 83, nr 4 (sierpień 2003): 713–17. http://dx.doi.org/10.1017/s0025315403007690h.

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The effect of dredging on bottom structure was assessed, to estimate the damage inflicted on the benthic macrofauna left on the dredge path and to evaluate aggregations of scavengers within the track. Sediment suspended during dredging rapidly resettled both on sand and sandy-mud bottoms. Dredge tracks were deeper on sandy-mud sediments and persisted longer than in sandy sediments. The disappearance of tracks in both sediment types depended both on current strength and wave action. Damage and mortality induced by dredging on the macrobenthic animals left on the dredge path was relatively low. Post-fishing SCUBA diver observations showed that damaged animals left on the dredge path rapidly attracted scavengers, mainly Ophiura albida. Immediately after the tow ophiuroids reached densities eight times greater in the track region than in the background. However, they dispersed again rapidly because only few damaged fauna were available on the dredge tracks. Undamaged or slightly damaged shellfish started to rebury immediately after escaping from the dredge.

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Zhenyu, AN, ZENG Guangming, ZHANG Shuofu, XU Min i WANG Lingling. "Effect of dredging engineering on water environmental capacity of Lake Dongting". Journal of Lake Sciences 18, nr 5 (2006): 509–14. http://dx.doi.org/10.18307/2006.0512.

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KIM, Tae-Hyeong. "Analysis of Hydraulic Effect by River Dredging in a Meandering Channel". Journal of the Korean Association of Geographic Information Studies 18, nr 4 (31.12.2015): 14–30. http://dx.doi.org/10.11108/kagis.2015.18.4.014.

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Yu, Y. R., Y. Chen, M. M. Dong i B. L. Yang. "Effect of cutter type on sediment pollutants release in channel dredging". IOP Conference Series: Earth and Environmental Science 39 (sierpień 2016): 012021. http://dx.doi.org/10.1088/1755-1315/39/1/012021.

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García-Oliva, Miriam, Ángel Pérez-Ruzafa, Georg Umgiesser, William McKiver, Michol Ghezzo, Francesca De Pascalis i Concepción Marcos. "Assessing the Hydrodynamic Response of the Mar Menor Lagoon to Dredging Inlets Interventions through Numerical Modelling". Water 10, nr 7 (20.07.2018): 959. http://dx.doi.org/10.3390/w10070959.

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The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. In recent years, changes in agricultural practices have induced an eutrophication process, leading to loss of water quality. As a solution, some management proposals have included dredging of the inlets in order to increase the water renewal. However, these proposals did not take into account the negative effects of previous experiences nor the consequences on environmental conditions of the lagoon and therefore on biological processes. The purpose of this work is to assess the effect that proposed mitigation measures, could have on the hydrodynamic conditions and discuss its possible ecological consequences. A three-dimensional (3D) numerical model has been used to simulate the lagoon under different dredging scenarios, covering different dredging depths and extensions. The simulated current fields and fluxes through the inlets, as well as water renewal times have been compared for the different scenarios. It is found that some of the considered scenarios take the system beyond the threshold of sustainability, where the modified current dynamics could affect sediment transport, beach dynamics and fishing capacities in a significant way. Water exchange with the Mediterranean is also strongly affected, with consequences for species connectivity, and a homogenization of the water renewal times that could lead to loss of ecosystem heterogeneity and structural complexity. The study demonstrates the utility of numerical models as effective tools for the management of coastal areas.

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Clarke, Sarah, i Oliver Tully. "BACI monitoring of effects of hydraulic dredging for cockles on intertidal benthic habitats of Dundalk Bay, Ireland". Journal of the Marine Biological Association of the United Kingdom 94, nr 7 (16.06.2014): 1451–64. http://dx.doi.org/10.1017/s0025315414000630.

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Hydraulic dredging for bivalves, such as cockles (Cerastoderma edule), has the potential to cause significant impacts on marine intertidal benthos. Although this fishing activity is common in northern European Natura 2000 sites such impacts may be incompatible with conservation objectives for designated habitats and species within these sites. In 2009–2010 a spatially nested control-impact study was undertaken before (t0), 8–9 days after (t1) and 4 months (t2) following dredging and extraction of 108 tonnes of cockles from a standing stock of 2158 tonnes in Dundalk Bay. This study failed to detect significant effects on benthic sediments, or the overall community structure. However, a fishing effect on the target species C. edule in one sampling area and a short lived effect on the bivalve Angulus tenuis were identified. Significant spatial and temporal variability in abundance of species and taxonomic groups, unrelated to fishing effects, was observed. Previous studies on the effects of fisheries on marine intertidal benthos have reported variable results, related to study design and objectives and the physical characteristics of the study site. Site specific studies, relative to the intensity and frequency of proposed fishing activity, may be required to adequately inform managers whether such activities are compatible with specific conservation objectives for Natura 2000 sites.

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Chen, Xi, Yanhua Wang, Tian Sun, Yu Huang, Yan Chen, Mingli Zhang i Chun Ye. "Effects of Sediment Dredging on Nutrient Release and Eutrophication in the Gate-Controlled Estuary of Northern Taihu Lake". Journal of Chemistry 2021 (19.01.2021): 1–13. http://dx.doi.org/10.1155/2021/7451832.

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Estuarine zones are regarded as the ecotones connecting the rivers and lakes. Sediment dredging is a conventional treatment technology that is widely used to remove the internal loading in estuarine zones worldwide. However, what is the characteristic of nutrient release in the gate-controlled estuary and how long this practice is effective are still unclear. Hence, sediment and water samples were collected from dredged and undredged regions around the gate-controlled estuary of northern Taihu Lake for laboratory experiments, in which they were subjected to different temperatures, depths, and disturbance levels. The total nitrogen (TN) and total phosphorus (TP) concentrations of the dredged region were lower than those from the undredged region under stable hydrodynamic conditions. A high dynamic release rate (R) of nutrients in the dredged sediments (RTN = 164.75 mg/m2·d and RTP = 5.83 mg/m2·d) existed under dynamic release conditions (stirring speeds: 90 and 120 r/min). The effect of disturbance and temperature on release rate and nutrient form was completely different for the static and dynamic release cases. The nutrient loads from dynamic release were 4–17 times greater than those from static release. For unstable hydrodynamic conditions, the release rate from the bottom sediment exceeded that from the surface sediment in the undredged region. These results indicated that, under stable hydrodynamic conditions, dredging improves long-term water quality. However, dredging alone in unstable hydrodynamic conditions may not remove the potential risk of internal release in the long term. Specific ecological and engineering measures should be combined with dredging practice to restore estuary habitats and minimize the release of internal pollutants.

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Getmanenko, V. A., E. G. Yanovskii i G. G. Grout. "Effect of Partially Mechanized Dredging on the Zoobenthos of the Eastern Sivash". Hydrobiological Journal 34, nr 2-3 (1998): 66–72. http://dx.doi.org/10.1615/hydrobj.v34.i2-3.70.

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Kim, Yuseung, Myunghan Lee i Yunjin Lee. "Test Study about Electro magnetic force effect to apply dredging soil transport". Journal of the Korea Academia-Industrial cooperation Society 16, nr 4 (30.04.2015): 2883–90. http://dx.doi.org/10.5762/kais.2015.16.4.2883.

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Płaska, Wojciech, Alicja Kurzątkowska, Edyta Stępień, Edyta Buczyńska, Joanna Pakulnicka, Agnieszka Szlauer-Łukaszewska i Andrzej Zawal. "The Effect of Dredging of a Small Lowland River on Aquatic Heteroptera". Annales Zoologici Fennici 53, nr 3-4 (sierpień 2016): 139–53. http://dx.doi.org/10.5735/086.053.0403.

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Guerrero, Massimo, Mariano Re, LeanDro David Kazimierski, Ángel Nicolás Menéndez i Rita Ugarelli. "Effect of climate change on navigation channel dredging of the Parana River". International Journal of River Basin Management 11, nr 4 (grudzień 2013): 439–48. http://dx.doi.org/10.1080/15715124.2013.819005.

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OSMANOV, Magomed Magomedovich, Frangiz Shamilievna AMAEVA i Ayshat Abdulmajidovna ABDURAKHMANOVA. "HYDROBIOLOGICAL STUDIES OF PLANKTON COMMUNITIES OF MAKHACHKALA SEAPORT". Herald of Daghestan Scientific Center of Russian Academy of Science, nr 74 (28.09.2019): 12–18. http://dx.doi.org/10.31029/vestdnc74/2.

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The article presents data from spring hydrobiological studies in the Makhachkala l Seaport during the period of dredging. It is noted that plankton of the studied water area of the Caspian Sea is a typical community of the spring period, formed mainly by marine and brackish-water species of phytoplankton and zooplankton. Diatoms mainly dominate in phytoplankton, and Copepods in zooplankton, where the main dominant is the Azov-Black sea invader Acartia tonsa Dana,1843. The analysis of planktonic communities indicates a rather developed quantitative and qualitative community of aquatic organisms with a characteristic abundance of species inhabiting it in the spring, despite a significant anthropogenic influence. It is established that the ongoing dredging operations do not have a tangible effect on the productivity of planktonic organisms.

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Jicheng, ZHONG, LIU Guofeng, FAN Chengxin, BAI Xiuling, LI Bao i YIN Hongbin. "Environmental effect of sediment dredging in lake:IV influences of dredging on microbial activity and functional diversity of microbial community in sediments and its significance". Journal of Lake Sciences 22, nr 1 (2010): 21–28. http://dx.doi.org/10.18307/2010.0103.

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Zhu, Xiao-Jun, i Feng Li. "Exploration on application of dredging thermal protection in the leading edge of the wing". International Journal of Modern Physics B 34, nr 14n16 (20.04.2020): 2040105. http://dx.doi.org/10.1142/s0217979220401050.

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Aiming at the severe aerodynamic heating problem in the leading edge of the hypersonic vehicle, in order to ensure the sharp shape of the leading edge of the wing, a dredging thermal protection structure is proposed, and the built-in high-temperature heat pipe structure is used to provide thermal protection for the leading edge of the wing. By means of numerical simulation and arc wind tunnel test, the dredging thermal protection structure of the leading edge of the wing is analyzed, and the thermal protection effect of the built-in high-temperature heat pipe is obtained. The numerical results show that under certain thermal conditions, the temperature at the leading edge of the wing decreases by 304 K, and the minimum temperature of the tail increases by 130 K. The heat flow is dredged from the high-temperature zone to the low-temperature zone, and the thermal load of the leading edge of the wing is weakened. The same result can be obtained by the arc wind tunnel test, which verifies the accuracy of the numerical method and the feasibility of the dredging thermal protection structure with high-temperature heat pipe embedded in the leading edge of the wing.

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Suryo, Sumar Hadi, A. P. Bayuseno, J. Jamari i A. Imam Wahyudi. "Analysis of Rake Angle Effect to Stress Distribution on Excavator Bucket Teeth Using Finite Element Method". Civil Engineering Journal 3, nr 12 (4.01.2018): 1222. http://dx.doi.org/10.28991/cej-030952.

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Excavator is mostly used for mining and construction. This heavy equipment, widely known as a backhoe, is a digging machine commonly used for dredging the mining materials, digging and leveling the soil, dredging the river, removing the road and demolition. Excavator has bucket teeth, component that frequently undergoes a change. The replacement of bucket teeth is performed due to its low usage time and many failure experiences such as wear, bend, crack and facture during the use. To prevent the occurrence of the failures, a structural analysis on bucket teeth is necessarily conducted. The analysis was conducted to find the stress distribution on bucket teeth from the rake angle effect during the excavation. The analysis was performed using finite element method by static loading and two-dimensional modeling to determine digging and resistive force in bucket teeth. Based on the analysis, it was obtained the stress distribution and maximum value of von misses occurring in the bucket teeth from the rake angle effect. The maximum stress, obtained from the analysis results, was then compared to the allowable stress of the bucket teeth material. The results showed that the materials used were in safe limits and had small potential for experiencing failure as well.

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Zhang, Xia Zhen, Xia Hong Zhang, Jing Xu Ni i Jie Zhuang. "Study on Curing Agent of Chemical Modification on Dredged Soil". Applied Mechanics and Materials 507 (styczeń 2014): 395–400. http://dx.doi.org/10.4028/www.scientific.net/amm.507.395.

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Large amount of dredged silt has been produced in the construction of water conservancy projects and oceanographic projects in China every year. Solidification and modification of dredging silt, to transfer it to good geotechnical materials, will be significant benefits on the sustainable development of the society. The curing effect of dredging soil isnt good if selecting cement as the single main curing agent. In this paper, the industrial steel slag and waste slag were chosen as the main curing agent and matching with cement and alkali activator, such as water glass, gypsum and sulfate. The help curing agent dosage range has been determined by single doped tests. Then the best ratio of GKCS curing agent has been determined through orthogonal tests. The research shows that the unconfined compressive strength can be achieved 5905kPa after using GKCS curing agent modified dredged soil.

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Hauge, Audun, Roger M. Konieczny, Per Ø. Halvorsen i Arild Eikum. "Remediation of contaminated sediments in Oslo harbour, Norway". Water Science and Technology 37, nr 6-7 (1.03.1998): 299–305. http://dx.doi.org/10.2166/wst.1998.0765.

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During the past 60-70 years, contaminated sediments from local rivers have been settling in the harbour basin of Oslo. This contamination, combined with that from other harbour activities, has developed into a serious pollution problem with both organic and inorganic contaminants. Since 1992 dredging activities have been restricted until the effect of dredging was determined and a safe disposal was found for the sediments. Because of this restriction, a conflict situation arose in terms of decreasing sailing depths, and dispersal of large quantities of contaminated sediments into the water column each day from ship traffic. A complete plan of action to remediate Oslo Harbour was started in 1994 and delivered to the State Pollution Control Authority (SFT) in August 1996. An evaluation of environmental risks connected to the remediation work has been carried out along with the determination of the requirements for the monitoring programme during and after the work. Preliminary evaluation of dredging techniques indicates that mechanic/hydraulic equipment will cause the least dispersion of sediment. Several options for treatment of the sediments have been evaluated. Study results point out that conditioning prior to disposal of the sediments in a confined disposal site in the harbour area, is the most cost effective solution. Seven disposal sites with a capacity of 0.5 mill. m3 have been identified. Two of the sites are integrated with a subsea road tunnel crossing the harbour basin. The other disposal sites will serve as new dock area after closure.

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CHU, Duc Thang, Gen HIMORI, Trong Vinh BUI i Shin-ichi AOKI. "An Experimental Study of the Effect of Offshore Bar Sand Dredging on Beach Erosion". Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 70, nr 2 (2014): I_531—I_535. http://dx.doi.org/10.2208/kaigan.70.i_531.

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Ye, Fei, Yinglong Zhang, Harry Wang, Hai Huang, Zhengui Wang, Zhuo Liu i Xiaonan Li. "Cross-Scale Baroclinic Simulation of the Effect of Channel Dredging in an Estuarine Setting". Water 10, nr 2 (7.02.2018): 163. http://dx.doi.org/10.3390/w10020163.

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Szostek, Claire L., Lee G. Murray, Ewen Bell, Gemma Rayner i Michel J. Kaiser. "Natural vs. fishing disturbance: drivers of community composition on traditional king scallop, Pecten maximus, fishing grounds". ICES Journal of Marine Science 73, suppl_1 (7.09.2015): i70—i83. http://dx.doi.org/10.1093/icesjms/fsv152.

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Abstract Scallop dredging is considered to be one of the most damaging forms of fishing to benthic habitats, although these effects vary among different habitats. The present study characterizes the biological communities that occur within the spatial limits of the English Channel king scallop dredge fishery in relation to key environmental drivers [mean seabed temperature; seabed temperature range; interannual temperature variation; bed shear stress (BSS); substrate characteristics; and depth] and across a gradient of scallop dredging intensity derived from vessel monitoring system data. Dredge fishing intensity was not correlated with species richness, species diversity, or species composition. However, increasing tidal BSS had a significant negative correlation with species richness and diversity. This outcome indicates that it is not possible to demonstrate that there is an effect of scallop fishing within the current spatial limits of the king scallop dredge fishery. This may be because historical dredge fishing could have already altered the benthic communities within the area of the scallop fishery to those that are resilient to scallop dredging, or that fishing disturbance has no impact over and above natural physical disturbance within the fishery. An analysis of biological and life history traits revealed that there was no relationship between recent fishing intensity, or BSS, and the functional composition of the communities present. However, even the lowest BSS values in the present study could be considered relatively high compared with areas outside the spatial boundaries of the fishery. Two distinct habitat groups were identified, based on the environmental drivers. These two groups were largely characterized by depth: deep (western) and shallow (eastern) sites. Species with traits that increase resilience to physical disturbance were abundant across all sample sites. Management concerning the environmental impacts of the fishery is discussed in terms of the spatial footprint of the fishery and predicted recovery time-scales for the associated benthic communities.

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Chusov, Alexander, Mikhail Shilin, George Gogoberidze, Julia Lednova i Nikolai Bobylev. "Experimental studies of benthos resistance to mechanical burying under the dredging material". E3S Web of Conferences 164 (2020): 01001. http://dx.doi.org/10.1051/e3sconf/202016401001.

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The goal of the fulfilled research is the study of the influence of the sedimentary suspension from the dredging material on the benthic hydrobionts. In laboratory aquariums six series of experiments were carried out with triple replication on the ability of different benthic organisms to dig out the soil strata due to their periodic burying by marine sand. These experiments were oriented on biota of Eastern Gulf of Finland and the Neva Bay, where a number of deposit sites for dredging material are located presently. Representatives of three main groups of hydrobionts of these areas were selected for experiments – Chironomidae, Gastropoda and Oligochaeta. The ability of different hydrobiont species to overcome the stress effect of the burying under the dredged material was estimated quantitatively. The results show, that the resistance of the studied species to mechanical burying is decreasing in accordance to the scheme: Chironomus plumosus > Melanoides tuberculata > Tubifex tubifex, and depends from the thickness of the layer of dredged material.

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Tang, Ya Ming, i Yang Tian. "Bionic Concave Pit-Like Metal Surface and Soil Direct Shear Test". Advanced Materials Research 569 (wrzesień 2012): 451–54. http://dx.doi.org/10.4028/www.scientific.net/amr.569.451.

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In order to test the reducing adhesion and resistance effect of bionic metal non-smooth surface, the direct shear test is experimented on a kind of bionic dredging tools with typical soil and bionic concave pit-like metal surface.The relation of shear force and shear displacement on a certain pressure is presented. The result will help to design the structure of cutting soil tools’ surfaces with less adhesion and resistance.

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Colby, Lisa H., Stuart D. Maycock, Frances A. Nelligan, Hilary J. Pocock i David J. Walker. "An Investigation into the Effect of Dredging on Tidal Asymmetry at the River Murray Mouth". Journal of Coastal Research 265 (wrzesień 2010): 843–50. http://dx.doi.org/10.2112/08-1143.1.

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Einarsson, Árni, i Margrét Lilja Magnúsdóttir. "The effect of sediment dredging on the distribution of diving ducks at Lake Myvatn, Iceland". Biological Conservation 66, nr 1 (1993): 55–60. http://dx.doi.org/10.1016/0006-3207(93)90134-m.

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Chan, Chee-Ming, i Ainun Nazhirin Abdul Jalil. "Some Insights to the Reuse of Dredged Marine Soils by Admixing with Activated Steel Slag". Advances in Civil Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/345134.

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Regular dredging is necessary for the development of coastal regions and the maintenance of shipping channels. The dredging process dislodges sediments from the seabed, and the removed materials, termed dredged marine soils, are generally considered a geowaste for dumping. However, disposal of the dredged soils offshores can lead to severe and irreversible impact on the marine ecosystem, while disposal on land often incurs exorbitant costs with no guarantee of zero-contamination. It is therefore desirable to reuse the material, and one option is solidification with another industrial waste, that is, steel slag. This paper describes the exploratory work of admixing dredged marine soil with activated steel slag for improvement of the mechanical properties. An optimum activation concentration of NaOH was introduced to the soil-slag mixture for uniform blending. Specimens were prepared at different mix ratios then left to cure for up to 4 weeks. The unconfined compressive strength test was conducted to monitor the changes in strength at predetermined intervals. It was found that the strength does not necessarily increase with higher steel slag content, indicating an optimum slag content required for the maximum solidification effect to take place. Also, regardless of the slag content, longer curing time produces greater strength gain. In conclusion, steel slag addition to dredged sediments can effectively strengthen the originally weak soil structure by both the “cementation” and “filler” effects, though the combined effects were not distinguished in the present study.

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Zhuang, Qian, Qi Ming Zheng i Dong Wang. "Analysis of Reasons for Siltation at Some Ore Wharf". Advanced Materials Research 765-767 (wrzesień 2013): 2922–25. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.2922.

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In the initial operation stage of some ore wharf, the silting situation appears in the wharf apron; through the on-spot hydrological, geological and topographic survey and combination with a lot of previous data and the project implementation, the research is made into the hydrodynamic sediment conditions in the water area and the changes of topographic erosion and siltation. The analysis shows that the siltation is related to many factors, including: the natural siltation effect, the effect of erosion adjustment period, the effect of sand excavation and dredging, and the effect of wharf construction. Among which, the local excavation in the rear of the wharf under construction has a great effect on the siltation of the wharf apron.

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Zhao, Shenghua, Yanlin Zhao, Jiang He, Zhenzhong Cao i Lei Wang. "Experimental Investigation of the Liquefaction Properties and Post-Liquefaction Volumetric Strain of Calcareous Sand in Dredger Fill Site". Advances in Civil Engineering 2020 (17.10.2020): 1–15. http://dx.doi.org/10.1155/2020/8821343.

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In this study, dynamic triaxial cyclic tests were conducted to examine the liquefaction properties and post-liquefaction volumetric strain of calcareous sand from a dredger fill site in the midst of the islands and reefs of the South China Sea. The test results indicated that there were some differences in micromorphology and composition between the calcareous sand obtained via dredging and natural calcareous sand. Axial cyclic stress attenuation can lead to higher cyclic vibration than actual liquefaction vibration, and the modified method can eliminate the effect of axial cyclic stress attenuation. Saturated calcareous sand liquefies under undrained and cyclic loading conditions, and the liquefaction resistance of the calcareous sand decreases with an increase of the effective confining pressure in the dense state. Calcareous sand obtained via dredging exhibited a higher liquefaction resistance compared with other types of calcareous sand. Furthermore, the proposed pore pressure development modified model better describes the pore pressure growth of the calcareous sand from the filling site. The fitting parameters of this model exhibited a high correlation with the relative density. Moreover, the post-liquefaction volumetric strain of the calcareous sand is larger than that of quartz sand, exhibiting a linear relationship with relative density.

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Pancrazi, Irene, Hassan Ahmed, Carlo Cerrano i Monica Montefalcone. "Synergic effect of global thermal anomalies and local dredging activities on coral reefs of the Maldives". Marine Pollution Bulletin 160 (listopad 2020): 111585. http://dx.doi.org/10.1016/j.marpolbul.2020.111585.

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Arizaga, Juan, Juan A. Amat i Manu Monge-Ganuzas. "The negative effect of dredging and dumping on shorebirds at a coastal wetland in northern Spain". Journal for Nature Conservation 37 (czerwiec 2017): 1–7. http://dx.doi.org/10.1016/j.jnc.2017.02.006.

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